Hi Folks...
Search and Rescue member here, telecom expert and host of the SAR prevention AdventureSmart series.
This meme, which has been circulating for years, is dangerously incorrect.
1) if your phone has no signal you can't change your voicemail
2) if your phone is low on battery voicemail is a waste of battery
Instead, please try to call 9-1-1 (or the emergency number where you are like 1-1-2, etc).
Here's why 🧵:
@Hiker_Scott @VeroniqueB99 @gwendolenau as a fmr. firefighter, I second this important #PSA!
Please just disable all power-consuming apps and data/WWAN, WiFi, Bouetooth, NFC.
Keep your phone on low power / energy saving.mode as long as possible.
In some jurostictions (i.e. #NewZealand) in case of disasters, mobile networks will restrict all non-emergency communications in suspected-to-be-affected areas to SMS and will even shutdown or at least downgrade mobile internet to save on battery and enable people in distress to call emergency services and make it easier for dispatch to get location details they can forward to people on the ground...
@kkarhan @Hiker_Scott @VeroniqueB99 @gwendolenau
And take a power bank with you. If the phone has run out of power the powerbank can be used at a later time to get the phone running again, once it makes sense again.
@Life_is @Hiker_Scott @VeroniqueB99 @gwendolenau OFC having additional batteries (i.e. #Fairphone) or at least some means to recharge a device (regardless if it's a powerbank or a car battery + DC/DC converter or whatever...) are always better than none.
Selectibg energy saving modes/settings and turning off all connectivity & apps beyond mobile telephony will greatly increase battery life ...
Scott M. 
Kevin Karhan 
C.Suthorn 